Pressure is building for greater use of video cameras to keep watch over the nation's cities

- particularly in transportation systems and other spots vulnerable to terrorism after the bombings in London.

The calls have come over the last few weeks as British investigators released surveillance footage of the bombers in the deadly July 7 attacks and then put out frames of suspects in Thursday's failed attacks.

"I do not think that cameras are the big mortal threat to civil liberties that people are painting them to be," Washington, D.C., Mayor Anthony A. Williams said Friday.

He's not alone. While privacy advocates question their effectiveness, Sen. Hillary Clinton called for New York City subway officials to install more cameras, even though officials said some 5,000 cameras are already in use across all modes of city travel. In Stamford, Conn., Mayor Dan Malloy said it's time to revisit a 1999 ordinance that limited cameras to watching traffic.

In many other spots around the country, cameras already are in place.

"In general, I think we're getting used to cameras. Hey, that's just the way the world is," said Roy Bordes, who runs an Orlando, Fla.-based security design consultant firm.

Consider these recent developments:

- Chicago now has at least 2,000 surveillance cameras across its neighborhoods, after leaders last year launched an ambitious project at a cost of roughly $5 million. Law enforcement says they've helped drive crime rates to the lowest they've seen in 40 years.

- In Philadelphia, where the city has increasingly relied on video surveillance, cameras caught an early morning murder which ultimately led to the capture of a suspect. Police say the accused is now a suspect in an unsolved murder from 1998.

- Homeland Security officials last week announced they would install hundreds of surveillance cameras and sensors on a rail line near the Capitol at a cost of $9.8 million, months after an effort by local officials to ban hazardous shipments on the line.

In most cases prior to the last few years, street crime _ not terrorism _ was the driving factor behind the cameras. There has also been a boom in traffic-monitoring cameras, and huge reliance on surveillance cameras in private business, especially in retail establishments like convenience and department stores.

Security experts say that technology hasn't yet caught up with hopes for the equipment, however.

They point out that despite London's huge network of cameras, the bombings weren't prevented. In those two cases, the cameras have only helped in the investigations.

One significant weakness is that the images caught by camera can't automatically link to a list of known terrorist suspects _ not that that would have helped in London, as men identified as bombers weren't on any watch lists.

"I haven't heard of anything being successful that allows us to prevent something by flashing up on a screen somewhere a positive identification of someone on a terrorist database," said Jack Lichtenstein with ASIS international, a Washington-based organization of security officials. Still, "that's where we're headed," he said.

Privacy advocates say the London bombings should persuade policymakers to stay away from surveillance rather than invest in it. It doesn't prevent terrorism, and at best only encourages terrorists to shift their target, they argue.

"Let's say we put cameras on all the subways in New York City, and terrorists bomb movie theaters instead. Then it's a total waste of money," said Bruce Schneier, author of "Beyond Fear: Thinking Sensibly about Security in an Uncertain World."

It's not much more likely to catch a terrorist than the random searches that New York officials have begun conducting on subways, he said. Better to spend money on intelligence resources to prevent attacks and emergency training to respond to them, he said.

But in Stamford, Conn., a city on a train line that runs to New York, Mayor Malloy said potential targets like trains, hospitals and water reservoirs should all be monitored, with regulations to guard against snooping on private homes, parks and other unlikely targets.

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